feat: prototype recvmmsg/sendmmsg batched datagram I/O

.github/workflows/build.yml

@@ -34,6 +34,53 @@ jobs:
           path: test-results/junit.xml
           if-no-files-found: ignore
 
+  # Linux with batched datagram I/O turned on. The recvmmsg/sendmmsg paths and
+  # their reliability-layer wiring are compiled out of every other job, so
+  # without this they would never even be built. Runs both suites so the
+  # batched send path is exercised over real loopback traffic.
+  linux-mmsg:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+
+      - name: Install OpenSSL
+        run: sudo apt-get update && sudo apt-get install -y libssl-dev
+
+      - name: Configure CMake
+        # Debug on purpose: this is the only job that compiles the mmsg paths,
+        # and RakAssert (which is compiled out unless _DEBUG) is what guards the
+        # invariants they rely on -- the SendBatch count-not-bytes return
+        # contract, the RNS2SendBatch reentrancy guard, the IPv4-only address
+        # branch. In Release those checks would not run anywhere.
+        run: |
+          cmake -B build \
+            -DCMAKE_BUILD_TYPE=Debug \
+            -DMAFIANET_BUILD_TESTS=ON \
+            -DMAFIANET_USE_RECVMMSG=ON \
+            -DMAFIANET_USE_SENDMMSG=ON
+
+      - name: Build
+        run: cmake --build build --parallel 4
+
+      - name: Run tests
+        run: |
+          ctest --test-dir build \
+            --output-on-failure \
+            --repeat until-pass:3 \
+            --timeout 600 \
+            --output-junit junit.xml
+
+      - name: Upload test results
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: test-results-linux-mmsg
+          path: build/junit.xml
+          if-no-files-found: ignore
+
   # macOS: Build and run both suites (unit + integration).
   macos:
     runs-on: macos-latest

.gitignore

@@ -14,6 +14,7 @@
 # Build directories
 build/
 Build/
+build-*/
 out/
 
 # Compiled libraries
@@ -46,4 +47,7 @@ Makefile
 
 # Package files
 *.tar.gz
-*.zip
+*.zip
+
+# Agent scratch space (plans, specs) -- kept on disk, never committed
+docs/superpowers/

Source/CMakeLists.txt

@@ -3,6 +3,13 @@
 # Copyright (c) 2024, MafiaHub
 # Licensed under MIT-style license
 
+# Batched datagram I/O (Linux). OFF by default; everything in MmsgBatch.h --
+# the helpers and the RNS2SendBatch accumulator alike -- is always compiled and
+# unit-tested, but the recvmmsg/sendmmsg syscall paths and their wiring into the
+# reliability layer only activate on Linux when these are ON.
+option(MAFIANET_USE_RECVMMSG "Batch UDP receives with recvmmsg (Linux only)" OFF)
+option(MAFIANET_USE_SENDMMSG "Batch UDP sends with sendmmsg (Linux only)" OFF)
+
 # Source files (explicit list, no GLOB)
 set(MAFIANET_SOURCES
     src/_FindFirst.cpp
@@ -47,6 +54,7 @@ set(MAFIANET_SOURCES
     src/LocklessTypes.cpp
     src/LogCommandParser.cpp
     src/MessageFilter.cpp
+    src/MmsgBatch.cpp
     src/NatPunchthroughClient.cpp
     src/NatPunchthroughServer.cpp
     src/NatTypeDetectionClient.cpp
@@ -200,6 +208,7 @@ set(MAFIANET_HEADERS
     include/mafianet/memoryoverride.h
     include/mafianet/MessageFilter.h
     include/mafianet/MessageIdentifiers.h
+    include/mafianet/MmsgBatch.h
     include/mafianet/MTUSize.h
     include/mafianet/NativeFeatureIncludes.h
     include/mafianet/NativeFeatureIncludesOverrides.h
@@ -337,6 +346,13 @@ function(mafianet_configure_target target_name)
         PRIVATE
             $<$<CONFIG:Debug>:_DEBUG>
             $<$<CONFIG:Release>:NDEBUG>
+        # PUBLIC so consumers including MmsgBatch.h / socket2.h see the same
+        # conditional declarations (RNS2SendBatch, the SendBatch override) the
+        # library was compiled with -- avoids a header/ABI mismatch when a
+        # downstream build turns batching on.
+        PUBLIC
+            $<$<BOOL:${MAFIANET_USE_RECVMMSG}>:MAFIANET_USE_RECVMMSG>
+            $<$<BOOL:${MAFIANET_USE_SENDMMSG}>:MAFIANET_USE_SENDMMSG>
     )
 
     set_target_properties(${target_name} PROPERTIES